Spoken language is a fundamental skill acquired during the first three years of life. However, a number of young children have language problems that begin to emerge during these years. Research has suggested that delays in language acquisition are associated with a number of negative social and academic outcomes (Fujiki et al., 1996;Rescorla, 2002), including 'acting-out'behaviors, which are commonly referred to as externalizing problems (Redmond &Rice, 1998). Further, both externalizing symptoms and language have been associated with lower levels of parental sensitivity and higher levels of parental rejection. However, little research has examined the role of parenting in the association between language delays and co-occurring externalizing symptoms. The proposed research was designed to explore the development of language problems and the association between emerging externalizing symptoms and language problems in a sample of low-income, high-risk children who were followed from the ages of 2 to 5. Specifically, the project will: 1) Explore trajectories of early language development including transient versus more permanent delays;2) Examine reciprocal associations between language problems and externalizing symptoms from ages 2 to 5;3) Study the moderating role of parenting in attenuating reciprocal effects between language and externalizing problems in early childhood. Group-based trajectory modeling, autoregressive structural equation modeling and multiple regressions will be the statistical tools used to explore these relationships. The findings of the proposed research should inform educators, clinicians and researchers with a more comprehensive picture of the early development of language problems, and associations between emerging externalizing symptoms and language problems. Further, if parenting is found to moderate associations between language and externalizing problems, this knowledge could lead to potential targets for future intervention. For example, if a child is displaying language problems, it may be possible for clinicians to intervene at the level of parenting as well as targeting language. Addressing both problems simultaneously may improve a child's language and decrease their risk for later externalizing problems.